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Related Experiment Video

Updated: Jul 18, 2026

Spatial Separation of Molecular Conformers and Clusters

Spatial Separation of Molecular Conformers and Clusters

Published on: January 9, 2014

Quantum phase interference and parity effects in magnetic molecular clusters

Wernsdorfer¹, Sessoli

¹Laboratoire Louis Neel, CNRS, BP166, 38042 Grenoble, France. Department of Chemistry, University of Florence, Via Maragliano 75/77, 50144 Firenze, Italy.

Science (New York, N.Y.)

|April 2, 1999

Summary

Researchers measured quantum tunneling in iron atom clusters, observing unique oscillations and a parity effect. This provides direct evidence of the topological quantum spin phase (Berry phase) in magnetic systems.

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Area of Science:

Quantum physics
Condensed matter physics
Nanotechnology

Background:

Molecular clusters of eight iron atoms exhibit nanomagnet properties at low temperatures.
These nanomagnets possess a spin ground state of S = 10.
Measuring very small tunnel splittings is crucial for understanding quantum phenomena in magnetic systems.

Purpose of the Study:

To develop an experimental method for measuring minute tunnel splittings in molecular clusters.
To investigate the behavior of tunnel splittings under an applied magnetic field.
To provide direct evidence of the topological quantum spin phase (Berry phase) in a magnetic system.

Main Methods:

Utilized a Landau-Zener model-based experimental technique.
Measured tunnel splittings in eight-atom iron clusters.
Applied a magnetic field along the hard anisotropy axis.

Main Results:

Observed oscillations in tunnel splittings as a function of magnetic field.
Attributed oscillations to topological quantum interference between two tunnel paths.
Identified a parity effect in transitions between quantum numbers M = -S and (S - n), analogous to half-integer spin suppression.

Conclusions:

The study successfully measured very small tunnel splittings in molecular nanomagnets.
The observed parity effect offers direct evidence for the topological component of the quantum spin phase (Berry phase).
This research advances the understanding of quantum effects in nanoscale magnetic systems.